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Autumn Irruptions of Red-Footed Falcons Falco vespertinus in East-Central Poland

Golawski A., Kupryjanowicz J., Szczypinski P., Dombrowski A., Mroz E., Twardowski M., Kielan S., Antczak K., Pagorski P., Murawski M.

Polish Journal of Ecology

2017

Vol. 65, nr 3

423--433

The red-footed falcon Falco vespertinus inhabiting SE Europe is known for its irruptive migrations. Here we attempt to outline the causes (weather conditions, dietary composition etc.) of the irruptions in 2014-2016 in east-central Poland. From 2004 to 2016 a total of 2873 falcons were counted during 542 observation bouts. The speeds of E and SE winds in August and September differed significantly between irruption and non-irruption years and were 1.3 km/h faster in the irruption years. Other weather factors, such as the number of days with E and SE winds, air temperature and the global North Atlantic Oscillation (NAO) and Scandinavia (SCAND) indexes, did not differ statistically between irruption and non-irruption years. The remains of 813 prey items were found in pellets collected in August and September, with a 93% dominance of insects; 84% of these were Coleoptera and Orthoptera. The irruptions of red-footed falcons in 2014-2016 may be also associated with increase in the number of breeding pairs in SE Europe.

Relation between stopover length and time and body parameters of European Robin Erithacus rubecula (L., 1758) during autumn migration (Central Poland)

Polak M., Szewczyk P.

Polish Journal of Ecology

2007

Vol. 55, nr 3

511-517

The relation between age, body parameters and the stopover behaviour of a small, short-distance, migratory bird during the season of autumn (August.October) was studied. Capture-recapture data of 1018 first-year and 89 adult European Robins migrating through central Poland ("Kaliszany" ringing station, 21 [degree] 48'E, 51 [degree] 05'N) in autumn between 1997 and 2005 were analysed. Body mass, length of wing and tail of young Robins caught and stayed at the stopover site showed significant seasonal variation. Immature Robins made longer stopovers (median = 4 days, 1.41) in the area than older ones (median = 3 days, 1.32). The stopover duration decreased continuously during the season. However, body mass changes at the staging site was not related to the age of birds. The birds migrating in the second half of autumn (late September.October) period accumulated fat faster than birds migrating in the early season. Our analyses confirmed that late migrants stayed for shorter stopovers and gained more body mass than early migrating birds due to a shift in migration strategy as an adaptation to time stress.